Thirteen-year growth response of ponderosa pine to various manipulations of understory vegetation was studied to determine if a threshold of understory cover can be established for plantation productivity and whether nitrogen-fixing Ceanothus species benefit plantation growth compared to non N-fixing Arctostaphylos species, given their ability to...

Foresters often lack information on growth of woody shrubs and their effect on conifer seedling survival and growth. Deerbrush (Ceanothus integerrimus H. & A.) was treated by several manual and chemical methods at age 3 and again at age 5 in a Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) plantation on a medium-quality...

Overstocked 70- to 90-year-old stands of ponderosa pine on medium- to low-quality sites were thinned in 1980 to 40, 55, and 70 percent of normal basal area and compared to an unthinned control. Mortality, diameter, and height in these northern California stands were measured annually from 1980 to 1987. After 8 years, mortality, primarily from mountain pine beetle (

Thinning and prescribed burning are common management practices for reducing fuel buildup in ponderosa pine forests. However, it is not well understood if their combined use is required to lower wildfire risk and to help restore natural ecological function. We compared 16 treatment combinations of thinning, prescribed fire, and slash retention for two decades...

Logging-damage surveys and tree-dissection studies were made in commercially thinned, naturally established young-growth true fir stands in the Lassen National Forest in northern California. Significant damage occurred to residual trees in stands logged by conventional methods. Logging damage was substantially lower in stands thinned using techniques designed to reduce...

On a site of above-average quality in northern California, an early shrub-forb-grass plant community was treated by artificially seeding two forage grass species at plantation age 3, cattle grazing with and without seeded grasses, and applying a soil-active chemical (Velpar). Planted ponderosa pines were part of this community. Results for a 10-year period (1988-1997)...

Overstocked 70- to 90-year-old stands of ponderosa pine on medium to low quality sites were thinned in 1980 to 40, 55, and 70 percent of normal basal area and compareh to an unthinned control. Mortality was recorded annually. Growth was measured every 5 years from 1980 to 1994. After 15 years, mortality, primarily from bark beetles and annosus root disease, was reduced...

Foresters often need information on the cost effediveness of manual and chemical release treatments for individual and combined species in young mixed-shrub communities. A study in northern Califomia evaluated five manual and chemical treatmcnts and their effect on several shrubs and grasses. Treatments were grubbing at age 1 to 2- and 4 ft (0.6- and 1.2-m) radii,...

Twelve-year-old Douglas-fir saplings on the Mad River Ranger District, Six Rivers National Forest, California were released by cutting competing vegetation in a 9-foot radius to test the timing and efficacy of this method in plantations older than those in which such work traditionally is doneÂ?the first 5 years. Nine years after release, the average stem diameter (3....

Thinning with removal of whole trees in a plantation or natural forest stand raises two main concerns ? soil compaction from the ground-based machinery and nutrient depletion particularly with whole tree harvest as is often practiced for attendant fuels reduction. To address these concerns, two sets of experimental treatments were imposed in young ponderosa pine...

The density and development of snowbrush, greenleaf manzanita, goldenbush (rabbitbrush), and graminoids were evaluated in a young California white fir plantation in northern California from 1986 through 1995. Manual grubbing and an herbicide created treatment regimes that lasted for 3 to 6 years and vegetation recovery times of 4 to 10 years. The timing and duration of...

In the late 1970s, the outlook for conifer seedlings in new plantations in the Western United States was dismal&too many were dying or growing below the potential of the site. This situation was untenable, and a large study aimed at increasing the survival and growth of planted conifer seedlings was implemented. This was the National Administrative Study on...

A 12-year-old ponderosa pine plantation on the Tahoe National Forest in northern California was mechanically treated with a Hydro-Ax in an attempt to increase the survival and growth of the planted seedlings. Other release methods were not feasible because the shrubs in the mixed-shrub community (greenleaf manzanita, mountain whitethorn, bittercherry, coffeeberry) were...

Overstory removal cutting, the most common means of converting old-growth stands to young growth stands in California, can produce excessive residues that pose management problems. Utilization is an attractive option for managing residues. However, the cost of residue retrieval and utilization is often prohibitive. Residue retrieval by a private contractor was studied...

Understorey vegetation plays a significant role in the structure and function of forest ecosystems. Controlling understorey vegetation has proven to be an effective tool in increasing tree growth and overstorey development. However, a long-term consequence of the practice on plant diversity is not fully understood. Here, we analyzed early development of overstorey and...

Soil compaction is known to limit plant growth by reducing soil macroporosity and restricting gas, water, and root movement. Recent evidence from study sites across the United States and Canada, however, suggests that tree growth is not universally affected by soil compaction from forest harvesting practices. Our observational study examined rooting patterns in mixed...

The density and development of greenleaf manzanita, other shrubs, and graminoids were evaluated in a young ponderosa pine plantation on a poor site in northern California from 1988 through 1997. Manual grubbing to a 5-foot radius created treatment regimes that lasted for 3 to 6 years and vegetation recovery times of 4 to 10 years. The duration and timing of the...